Hardwood floor systems provide numerous advantages over other types of floors. Due to surface uniformity, aesthetics and injury reduction which results from a high degree of resiliency, many athletes and exercisers prefer hardwood floor systems over floors made of other materials.
One well-recognized disadvantage of hardwood floor systems relates to moisture. The maple floorboards commonly used in hardwood floor systems expand and contract from moisture absorption and drying out, respectively, due to the varying levels of humidity in the air during the four seasons of the year. In many cases, the horizontal expansion and contraction forces may eventually cause the floorboards to vertically raise up at locations of least resistance. Sometimes this vertical raising can be detected visually. Other times, it becomes noticeable only as a "dead spot" in the floor during athletic activities. Regardless, the performance of the floor may become seriously impaired as a direct result of horizontal expansion and contraction caused by moisture content.
Sleeper-type floor systems reduce the adverse effects of moisture. In a sleeper-type floor system, the floorboards are held in spaced relation above a base by parallel supports which are referred to as "sleepers". This spacing enables air to circulate between the base and the floorboards, thereby eliminating direct transfer of moisture therebetween. Anchoring of the sleepers to the base further minimizes the adverse effects of expansion and contraction due to moisture.
As with all hardwood floor systems, it is desirable to construct sleeper-type floor systems which also have a sufficiently high degree of resiliency. The resiliency of a floor system may be quantified by measuring a number of performance characteristics, including shock absorption, deflectability and deflectability containment. The resilience of a floor system plays an important role in minimizing impact-related injuries.
U.S. Pat. No. 4,856,250, entitled "Sleeper For The Attachment of Covering Material To A Surface", discloses a sleeper-type hardwood floor system with anchored and resilient characteristics. The floor system disclosed in this patent achieves a relatively high degree of resilience by providing an inverted, T-shaped nailing strip supported on a foam strip within a guideway. An upper portion of the strip protrudes above the top of the channel, and a lower, wider portion of the strip resides below opposing tabs of the guideway. Fasteners secure the channel to a concrete base. The channel is anchored to the base prior to moving the pad and nailing strip therein. This construction enables the nailing strips to deflect downwardly upon impact, but prevents them from vertically raising, as may occur during expansion or contraction. In short, it is primarily the sleeper construction which provides the anchored and resilient characteristics for the floor system.
Unfortunately, the sleeper disclosed in U.S. Pat. No. 4,856,250 can be relatively difficult and expensive to install, due to separate shipping of the sleeper components to the job site and a multi-step, labor-intensive installation of these components. More particularly, to install the floor system disclosed in U.S. Pat. No. 4,856,250, the guideways must first be mechanically fastened to the base, with every other guideway in each row offset from the next adjacent guideways to permit lateral access therein. Then, a resilient foam strip must be slid horizontally into the channel. Finally, an inverted, T-shaped nailing strip must be slid horizontally within the guideway, between the foam strip and the two opposing tabs. Thus, sleeper installation requires three separate steps. Floorboards are then nailed to the nailing strips.
While the combined vertical dimension of the foam strip and the nailing strip is less than the inside vertical dimension of the guideway beneath the tabs, it can become extremely difficult to horizontally slide the elongated foam strip and the elongated nailing strip along the entire length of the guideway. If the nailing strip is warped at all, the horizontal sliding becomes even more difficult. Because of the manner of inserting the foam strip and the nailing strip, the sleeper length must be kept relatively short.
Also, with this sleeper assembly, the tolerance of the Vertical dimension of the form strip and the nailing strip with respect to the vertical dossimer of the channel must be made fairly high. Otherwise, it would not be possible to slide the components into the channel. However, with this higher tolerance, the actual vertical dimensions of the sleeper components may vary along their lengths. These dimensional variations may cause variations in loading characteristics along the length of the sleeper. As a result, the surface of the floor system will not be uniform in response to an applied load.
Another disadvantage associated with on-site installation of the separate components of this sleeper relates to the consistency and accuracy of securing the guideways. To support the floorboards properly, the bottoms of the guideways must directly contact the base, or leveling shims supported on the base, and the fasteners must be driven into the base at a 90.degree. angle. Otherwise, the guideways may be susceptible to longitudinal or transverse expansion or contraction forces. Moreover, if the heads of the fasteners protrude too far upwardly, the lateral movement of the foam and nailing strip during installation may be impeded. Because these fasteners are usually driven through the bottoms of the guideways by a hand-held gun, there is no guarantee that they will be consistently driven into the base at the preferred 90.degree. angle.
It is an objective of this invention to simplify and reduce costs associated with the shipping and installation of sleepers used to support an anchored and resilient hardwood floor system.
It is another object of the invention to meet tighter tolerances with a sleeper for an anchored and resilient floor system, thereby to enhance the uniformity of the load-response characteristics of the floor.
It is still another object of the invention to accurately and consistently install the sleepers of an anchored and resilient hardwood floor system.
The objectives of this invention are achieved by providing a prefabricated sleeper that may be easily manufactured in a shop and then shipped to the job site in a form which is ready to be installed. The invention contemplates a prefabricated sleeper which includes an elongated channel and a nailing strip supported on a plurality of pads within the channel, wherein the nailing strip has at least one vertical access hole formed therethrough to provide simple and direct access to the bottom of the channel to facilitate securement to a base.
During installation, a fastening gun is inserted within the access hole and into contact with the bottom of the channel. The sizing of the gun and the access hole requires that the gun be oriented at 90.degree. in order to contact the bottom of the channel. In this position, a fastener may be shot out of the gun at a 90.degree. angle, through the bottom of the channel and into the base.
This prefabricated sleeper provides both anchoring and resiliency for a hardwood floor system. At the same time, this prefabricated sleeper significantly reduces the time and cost associated with installing an anchored, resilient hardwood floor system. Moreover, shipping costs for this prefabricated sleeper are minimized, because only one, preassembled sleeper construction must be shipped, rather than multiple components.
According to a preferred embodiment of the invention, this prefabricated sleeper includes an elongated steel channel. The channel has a bottom and two parallel, spaced sides. Upper ends of the sides are turned in to define flanges which enclose the top of the channel and define a "C" shape, in cross section. A plurality of compressible and deflectable pads are located within the channel. An elongated, inverted, T-shaped nailing strip is supported by the pads and is also located within the channel. An upper portion of the nailing strip extends above the partially enclosed top of the channel. An enlarged bottom portion of the nailing strip is defined by two shoulders, each of which is located below one of the flanges of the channel. A plurality of vertical access holes extend vertically through the nailing strip, thereby to provide direct access to the bottom of the channel to facilitate mounting to a base in prefabricated form.
The structural arrangement of these components provides a sleeper with a tighter dimensional tolerance. Thus, the load-response characteristics of this prefabricated sleeper are the same along its entire length. This enhances the overall capability of the floor system for providing uniformity in resilient, load-response characteristics.
To manufacture this prefabricated sleeper, an elongated wood strip is milled to form a T-shape. After milling the strip to a T-shape, a plurality of access holes are drilled through the nailing strip. The access holes extend from an enlarged first end of the T-shape to a reduced second end. A plurality of pads are then mechanically fastened to the enlarged end of the T-shaped strip, with the pads spaced away from the access holes. Preferably, the pads are stapled to the nailing strip. An elongated strip of steel is then located adjacent the pads, rolled around opposite sides of the nailing strip and then turned inwardly beyond the shoulders of the nailing strip. This partially encloses the nailing strip, with the upper portion extending beyond the turned-in edges. In this form, the prefabricated sleeper is ready for shipment to the job site.
At the job site, the prefabricated sleepers are preferably laid end to end in parallel rows. The sleepers should be oriented in a direction which is perpendicular to the final orientation of the floorboards. Preferably, adjacent rows of sleepers are staggered so that the ends of the sleepers are offset. Floorboards may then be secured to the nailing strips via nails driven through the floorboards and into the upper portions of the nailing strips.
In a preferred floor system utilizing this prefabricated sleeper, a layer of panels is located between the floorboards and the sleepers. The panels are secured to the sleepers, and the floorboards are secured to the panels. This layer of panels provides an additional degree of uniformity and stability for the floor system. If desired, additional layers of panels may be used, either with or without floorboards secured to an uppermost layer of the panels.